Method for producing high-purity scandium oxide

Abstract

Provided is a method for obtaining high-purity scandium oxide efficiently from a solution containing scandium. The method for producing high-purity scandium oxide of the present invention has a first firing step S12 for subjecting a solution containing scandium to oxalation treatment using oxalic acid and firing the obtained crystals of scandium oxalate at a temperature of 400 to 600° C., inclusive, a dissolution step S13 for dissolving the scandium compound obtained by firing in one or more solutions selected from hydrochloric acid and nitric acid to obtain a solution, a reprecipitation step S14 for subjecting the solution to oxalation treatment using oxalic acid and generating a reprecipitate of scandium oxalate, and a second firing step S15 for firing the reprecipitate of obtained scandium oxalate to obtain scandium oxide.

Description

TECHNICAL FIELD[0001]The present invention relates to a method for producing scandium oxide, and more specifically, to a method for producing high-purity scandium oxide in which the amount of impurities is reduced.BACKGROUND ART[0002]In recent years, scandium that is attracting attention as a high-performance alloy with aluminum or a material for a fuel cell is mainly purified from titanium purification residues or a leachate obtained by leaching a nickel oxide ore with sulfuric acid, and recovering of scandium as a by-product has been advanced.[0003]In such recovering of scandium in the related art, mainly, production of a high-purity product is performed by a solution purification treatment in which impurities are separated. That is, since scandium exists in a solution (for example, a leachate or the like) in a main step as mentioned above at a low concentration, it is necessary that scandium is gradually concentrated by performing methods such as an ion exchange method and a solv...

AI Technical Summary

Benefits of technology

The invention provides a way to get high-purity scandium oxide from a solution containing scandium.

Problems solved by technology

By using those methods, the purity is increased to a grade necessary for an alloy, for example, a grade of 99.9% (3N product) or more, but it takes considerable time and effort, and this causes cost required for purification to remain high.

However, in the method of Patent Document 1, since impurities coexisting in the same amount as scandium or coexisting in a far larger amount than scandium are separated, there are problems in that time and effort and cost required for separation of impurities increase, and impurities are unable to be completely separated.

However, even if an attempt is made to use such a method with respect to scandium oxide, scandium oxide is sparingly soluble in an aqueous solution of acid or the like, so that it is necessary to use a high concentration of acid in order to dissolve scandium oxide.

Further, even if an attempt is made to perform oxalate formation again, since the acid concentration is high, it is necessary to add about 12 equivalents of oxalic acid in order to obtain an actual yield of about 80%, and thus a problem arises in that the cost of chemicals increases.

As described above, in the method of related art, in the case of obtaining high-purity scandium oxide, it takes considerable time and effort and the cost increases, and further, there is an issue that handling of high concentration of acid causes a safety problem.

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